Five thousands litres of iron sulphate spilt from a chemical works on Riverwalk Road in Enfield last night. A static storage tank ruptured and the chemical leaked into the roadway.
The industrial estate was evacuated and 40 people were removed to a place of safety.
Following liaison with the Environment Agency fire crews contained the contaminated water and it was removed by a suction tanker.
The Brigade was called at 1645 and the incident was over by 2146. Firefighters from Enfield, Bethnal Green, Euston, Chingford, Woodford, Edmonton, Tottenham, Walthamstow and Ilford fire stations were at the scene.
The Environment Agency is working with the site to complete the removal of residual contamination from the roadway.